MSH2 and cancer: Nineteen genes in the set have a unique human ortholog (Table 2) and, of these, 12 (UBX4, IDP1, IDP2, MSH2, RAD1, TOP2, NBP2, MUS81, RAD54, DBF2, STP22, PBS2) are orthologous to cancer genes as annotated in the Cancer Gene Index (CGI [17]).